Electronic multiplier



1952 w. WOODS-HILL ETAL 2,623,115

ELECTRONI C MULTI PLIER Original Filed March 3, 1950 B Sheets-Sheet l INVENTORS DAVID T. DAVIS WILLIAM WOODS-HILL BY agazmb ATTORNEY Dec. 23, 1952 w. WOODS-HlLL ETAL 2,623,115

ELECTRONIC MULTIPLIER Original Filed March 3, 1950 8 Sheets-Sheet 2 ms 'I' EJQ- INVENTORS DAVID T. DAVIS WILLIAM WOODS-HILL BY 5 ATTORNEY Dec. 23, 1952 w. woons-Hlu. ETAL 2,623,115

ELECTRONIC MULTIPLIER Original Filed March 3, 1950 8 Sheets-Sheet 3 INVENTORS DAVID T DAVIS wmum wooos-mu.

A TTORNE Y Dec. 23, 1952 w. WOODSHILL ETAL ELECTRONIC MULTIPLIER Original Filed March 3, 1950 8 Sheets-Sheet 4 INVENTORS DAV/D T DAV/5 WILLIAM WOODS-HILL ATTORNEY Dec. 23, 1952 w. wooos-r-uu. ETAL 2,623,115

ELECTRONIC MULTIPLIER Original Filed March 3, 1950 8 Sheets-Sheet 5 INVENTORS DA V/D T DA V/S WILL MM WOOD-5 -///LL A T TOR/V5 Y D 1952 w. WOODS-HILL ETAL 2,623,115

ELECTRONIC MULTIPLIER Original Filed March 3, 1950 8 Sheets-Sheet 6 4.; v I -i B INVENTORS DAV/D 2' DAV/5 WILL/AM WOODS H/LL A TTORNE Y Dec. 23, 1952 w. WOODS-HILL ETAL 2,623,115

ELECTRONIC MULTIPLIER 8 Sheets-Sheet 7 Original Filed March 3, 1950 A B 1:: \b

-' mmvroxs T DAV/D I DA ws a; L 2 By WILLIAM woons mu.

ATTORNEY Patented Dec. 23, 1952 UNITED STATES PATENT OFFICE ELECTRONIC MULTIPLIER Original application March 3, 1950, Serial No.

147,141. Divided and this application December 27,, 1950, Serial No. 202,916.

Britain March 24. 1949 2 Claims.

Multlplicand Product y Register Counter Multiplier Register 5. d s. d

Decimal Number:

99 2 9. l8. .2 4 l9. l6. 4 8 4 8 4 317. l. 4 8 634. 2. 8

Product 980. 18. (i

It is an object of the present. invention toutilize this principle of multiplication employing purely electronic circuits including a novel selective impulse generator, so that mlfltiplicatlon may be p rf m extremely rapid y- With this apparatus employing the above enunciated principle, multiplicationmay be performed when one or both of theiactors is expressed in a non-uniform system. Such as sterling currency or hours and minutes. 1

The term digit will be usfid. herein to denote all numbers less than the radix of the scale of notation employed. Thus, in the dumdecimal notation, and ll-wlll bedeemcd to be digits. The term gate tube or simply gate ill be used to describe a tube such as a pentode. for example, comprising more than three electrodes, the tube being so arranged that a. voltage impulse applied to one electrode may be prevented from appearing at a second electrode used as an output electrode by the application of acontrol voltage to a third electrode. An example of such a gate is a pentode in which the voltage impulse is applied to the control grld,the anode is the output elec trade and anegative control voltage may be applied to the suppressor 'g'rld.

In Great According to the invention, a complete clectronic multiplying device comprises a pulse generator, a pulse emitter, an electronic multiplier (MP) register, an electronic (MC) multiplicand register, an electronic (PR) product counter, an electronic odd-even detector to determine whether the value standing in the multiplier register is even or odd, and means under control of the emitter for repeatedly halving the value registered in the multiplier register and doubling the value registered in the multiplicand register, and novel selective impulse enerating means under joint control of the multiplicand register and the odd-even detector for transferring into the product counter the value registered in the multiplicand register only when th multiplier is odd.

Throughout the specification the term tube will be used to refer to thermionic tubes of the high vacuum type.

The invention will be described by a specific example in which an amount in pounds, shillings and pence is multiplied by a decimal amount.

.Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings. which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Figures 1 and 1a taken together with Figure l at the left and id at the right comprise a block diagram of the complete electronic multiplying device.

Figure 2 is a circuit diagram of one emitter unit 30(1) of Figure 1.

Figure 3 is a circuit diagram of the pulse generating circuit, including a. multivibrator, all indicated generally as 3| in Figure 1.

Figure 4 is a circuit diagram of the start con trol circuits indicated generally as 39 in Figure 1.

Figure 5 is a circuit diagram of one of the auxiliary control units each indicated as 54 in Figure 1.

Figure 6 is a circuit diagram of one of the auxiliary control units each indicated as 55 in Figure 1.

Figure 'I is a circuit diagram of one denomination of the multiplier register indicated as 4! in Figure l and of the odd-even detector, indicated as F2 and Q in Figure 1.

Figure 8 is a circuit diagram of one denomination of the multiplicand register indicated as 42 in Figure}.

Figure 9 is a circuit diagram of one denomination of the product counter indicated as 43 in Figure 1.

Figure is a circuit diagram of the auxiliary control unit 58 of Figure 1.

Figure 11 is a diagrammatic representation of the complete multidenominational product counter.

Figure 12 is a circuit diagram of the cycle counter 40 of Figure 1 and Figure 13 is an explanatory chart indicating the purpose and relative timing of the various control pulses produced by the emitter during one multiplication cycle.

In order to make clear the method of operation of the complete multiplying device, the functions of the major parts will be described with particular reference to Figure 1, followed by a detailed description of the operation of the individual units. Finally, the individual steps making up a complete multiplication cycle will be detailed in the order in which they occur.

General Referring to Figures 1 and la, the complete multiplying device consists essentially of four major parts, a multiplier register 4| of tens and units orders, a multiplicand register 42 of tens of pounds, pounds, tens of shillings, shillings and pence, a product counter 43 of tens of pounds, pounds, tens of shillings, shillings and pence, an emitter consisting of nineteen units, a half cycle trigger control unit I00, a pulse generator 3| which includes a multivibrator (MV), a start control circuit 39 including a start key and a cycle counter 40.

Entry of values into the multiplier and multiplicand registers is made in the binary code of 1, 2, 4, 8 in each denomination. Thus to enter the value '7 in a denomination of the multiplicand register, a pulse is applied to the lines I I (Figure 8) marked 1, 2 and 4, thus setting the trigger units representing #1, #2 and #4, as described later.

The first half cycle of the emitter is employed. as described in detail later, to test the original MP value, before it is halved, for odd or even. If it be odd, the transfer pentodes 44 are rendered operative so that during the first half cycle, the original value of the MC, before it is doubled, is transferred, as described in detail later, to the products counter.

The multiplier register is so arranged that after the first half cycle upon applying control pulses from the emitter, the value standing in the register may be halved, and under control of pulses from the emitter the value standing in the multiplicand register may be doubled. Thus under control of the emitter, the entered multiplier value is halved and simultaneously the entered multiplicand value is doubled. The two units F2 and Q together (Fig. 10) form the odd-even control and determine whether the halved value standing in the multiplier register is even or odd and control the transfer of the doubled value in the multiplicand register to the product counter. If the multiplier value is odd, then the odd-even control allows the doubled multlplicand value at that time to be transferred from MC register 42 to; register 43 via. the gates generally indicated a Having transferred this doubled MC value to the products counter. the halving and doubling is carried out a second time, providing a second doubled value which may be transferred and added to that already in the DtQdllQ iS QQunter, to

successively build up the final product in the manner shown in the example. These operations of halving, doubling, and transfer to the products counter, if the halved value is odd, are continued for a fixed number of cycles, The number of cycles is determined by the cycle counter 40 and is sufficiently large to ensure that the greatest number which can be entered in the multiplier register will have been reduced to unity by successive halving when the cycle counter causes the operations to cease. It may happen that the multiplier register reaches unity at some cycle earlier than the last. On the next cycle the multiplier register will be reduced to zero and remain so set for the remaining cycles. Since zero is sensed by the odd-even detector as an even number, no entries will be made into the products counter after the one when the multiplier register has reached unity, thus retaining the correct answer even though additional cycles occur between the obtaining of the answer and the cessation of operations.

The nineteen emitter units 30 provide impulses and voltages to control the operation of the registers and the product counters. The units operate in succession in the order 1 to 19 and this operation occupies the first half of one multiplying cycle, The half cycle control unit I00 enables the same nineteen emitter units to provide a further group of impulses controlling the second half of the multiplying cycle, in a manner to be described.

Pulse generator This unit is indicated generally as 3| in Figure l and the circuit is shown in detail in Figure 3. The function of the unit is to provide a series of pulses of uniform amplitude and recurrence frequency to control the relative time relationship of the various functions performed durin a multiplying operation.

The two triodes I06 and I0! with the crosscoupling networks of condenser l Iii-resistor I09 and condenser 1 l i-resistor I08 form a relaxation oscillator or multivibrator which operates in a well known manner to produce at the anode of triode I01 voltage variations of substantially square wave form. These two resistor-condenser networks form the frequency determining elements and have equal time constants so that the durations of the positive and negative half -cycles of the square wave form are equal.

This square wave is applied through condensers Ill and H5 to the grids of the triodes H3 and III, which together form the trigger circuit 91. This input switches the trigger 91 through the "on and olP' states for each cycle of the square wave, producing at the triode anodes a voltage variation which is also of square wave form, but approaches more nearly to the ideal square wave form than the input.

When triode H3 becomes non-conducting, a positive pulse is applied to the grid of the tube 98. This tube is normally non-conducting, since the grid is connected through resistor l i 6 to the negative'bias line 4, but the amplitude of the applied positive pulse is such that the tube conducts on the peak of the pulse, producing a square negative-going pulse of uniform amplitude in the anode circuit. When triode H2 becomes non-conducting, by similar action a negative pulse is produced at the anode of tube 99. Since triodes H2 and H3 become non-conducting alternately, negative pulses will be produced 9 l nes 8 d 33 alternately. The pulses on l n s .32 and 33 are employe 10.1 the successive resetting of the emitter uni s, as will be expla n d- In a d on. posi ive pulses are applie via line B 6 from the anode of t iode H3 to the control grids of the pentodes TI and T2 in the start control unit (Figure 4) Start control This .unit indicated generally .as 39 in Fig. l governs the initial starting 01 the emitter units for per-formin a multiplication operation, the successive emitter cycling and the final stopping of the emitter at the completion of the requisite number of cycles.

The two pentodes 'TI ,and T2 (Figure 4) to whose control grids plus pulses are applied via line 86 as stated above have these grids joined together and connected to "bias line 4 through resistor NH. The suppressor grid of TI is connected to the mid-point of the left-hand potentiometer formed by the two ,egual resistors ill and the suppressor grid of T2 is similarly connected to the right hand potentiometer. These two potentiometers are connected "between the earth line I and the main negative supply line I5. l-n the-normal posit-ion the lgey B bypasses a resistor SI and connects the suppressor grid of TI directly to line i. The suppressor grid of T2 is biased beyond cut oil by the potential developed across the right hand upper resistor 9|, and the control grids of TI and T2 are also biased beyond cut off by the potential of line 4.

The above mentioned positive pulses applied to the grids of TI and T2 from the pulse generator (Figure 3-) via line 86 are of such amplitude that with key 90, as shown, a negative pulse is produced at the anode of TI and applied to the grid of the triggervtube U through condenser on. Since the anode current of T2 is cut oil by the bias on the suppressor grid, no pulse appears at its anode. Thus the negative pulses ap plied to the grid of tube U ensure that it is nonconducting and thus that V is conducting which is contrary to the generally normal status of these triggers.

When the key 90 is momentarily depressed, the suppressor grid of T2 is connected to earth and the suppressor grid of Ti biased beyond cut off. Accordingly, the next positive pulse on line 86 causes T2 to pass anode current and the negative pulse at its anode is applied to the grid of tube V through the condenser I03. This causes V to become non-conducting and the trigger UV switches over to the other stable state, with U conducting and V non-conducting. The conduction of tube U causes a drop in voltage at the anode and consequently a negative pulse is sent via line 92 to another trigger circuit consisting of tubes X and Y. This pulse switches this circuit from the normal state, with X conducting and Y non-conducting, to the opposite state with Y conducting and X non-conducting. As a result of the drop in potential at the anode of tube Y, a negative pulse is applied via line 81, and condenser I04 (Figure 2) to the grid of tube I05'of trigger unit (1) of the emitter chain, to switch this trigger to the reverse condition. At the same time, cessation of anode current in tube X (Figure 4) reduces the potential drop across resistor I46. The resistors I46, I41 and I48 form a potentiometer between the H. T. line 2 and the main negative supply line l5, so that the potential at the junction of resistors I 41 and I48 o r se L n 95' iohas this. junction. to the suppressor grid of gate Z, which therefore under- *KQQS :3 similar rise in potential.

potential. This conditioning of the suppressor rid of this gate 2 cooperates with a plus pulse on the control grid as described later to produce a negative output pulse on line 89 to initiate all operations of the emitter subsequent to the first k6? operated.

When. key v is released, TI becomes capable of conduction once more. so that negative pulses #118 applied to tube LT :and the trigger circuit UV is back to the normal condition. However, as he explained in connection with the emitter units, the resulting positive pulse on but 52 is not effective to switch trigger circuit KY, remains with X non-conducting. depression of the key 5.0 has resulted in a pulse being applied to emitter unit (1) and the trigger .XY being switched to the reverse state, bringing the suppressor grid of gate Z to approximately cathode potential The trigger XY remains in this state :until the end of the multiplying operation, when a pulse from the cycle counter .40 is applied via line 88 to the grid of tube Y to switch the trigger circuit back to its normal stateat which time the whole start control unit has 'retumed'to the normal state.

Cycle c unter As stated above, the multiplying device performs a fixed number of cycles irrespective of the actualvalue of'the factors. The cycle counter 40 (Figure 19 shown in detail in Figure 12, determines the number of cycles performed.

The counter consists of four trigger stages 94 (Figure 12) arranged to form a, binary counter, the stages representing respectively the values 1. 2, 4 and 8. Each stage consists of two triodes cross-coupled by a network of resistors and condensers in such a way that the circuit possesses two stable states, with either the first triode conducting and the second non-conducting, 01 the first non-conducting and the second conducting. The #1 trigger state 94 representing the value "1" will be considered as an example. The resistors I28, I26 and I20 form a, potentiometer between the H. T, line 2 and the negative bias line 4. The anode of triode H8 is connected to the junction of I29 and I26 and the grid of triode II! is connected to the junction of I26 and I29. The resistors I28, I21 and HI form a similar potentiometer to which the anode of H9 and the grid of I18 are-connected. By suitably choosing the values oi the resistors forming the potentiom-- eter chains, the additional voltage drop across resistor I29 caused bytriode I I3 conducting fully, lowers the potential at the junction of I25 and I20 sufiiciently to drive the grid of triode I I9 considerably more. negative than the cut-off value. Triode. U915 consequently drawing no anode current and the 'potentialat the junction of resistors HI and I28 is such that triode H8 is kept conducting fully- Since the circuit is symmetrical, it will be appreciated the reverse state of the tube conduction will result in a second stable state. 11' a. negative pulse-is applied to the grids of H3 and I I9 via line III and the two condensers I22 and I23, the conducting triode will be cut off and in cruisequencev the trigger stage will be switched over to assume the other stable condition. The condensers I24 and I25 assist in ensuring a rapid switch-over from one state to the other. A similar type of trigger stage is used in other parts of the apparatus; for example the trigger 91 of the pulse generator shown in Figure 3, and it may be noted that the mode of operation is the same. Unless the contrary is stated, it is assumed that when a trigger stage is in the normal or "off" state, the left hand tube is conducting and the right hand non-conducting.

When a pulse is applied to line I I7, trigger stage #1 will be switched from the off" to the on" state, with the result that a positive pulse is applied via line I30 to the grids of the tubes comprising the next trigger stage, but is ineffective to switch it. However, on receipt of a second pulse on line III the #1 trigger stage is switched back to the "of!" state and the resulting negative pulse on line I30 switches trigger stage #2 "on. It will be apparent that the other trigger stages will operate similarly and that the four stages together constitute a binary counter counting up to sixteen, any value being represented by the appropriate stage or stages being in the on" condition.

The line III (Fig. l) is connected to the last (19) of the emitter units 30 (Figure 1) and as will be explained, receives one pulse for each multiplying half cycle. Thus the counter will have received sixteen pulses when the emitter has completed eight full cycles. This sixteenth pulse switches trigger #8 back to the "01? state, so that a negative pulse is applied via counter output line 08 to the control grid of conducting triode Y in the start control circuit (Figure 4) to reset trigger stage XY, which has the effect of allowing a further half cycle to take place but prevents the emitter unit (1) from commencing a further cycle.

Emitter unit The emitter chain consists of nineteen units, generally designated 30 (Figure 1) and individually numbered 1 to 19. The units all perform the same function of supplying controlling pulses and voltages and are generally similar in operation. The circuit of the first unit 30(1) will be described with reference to Figure 2 and then modifications in other emitter units will be noted.

The two triodes I and I32 (Figure 2) form a trigger stage with two stable states, generally similar to those of the cycle counter (Figure 4). However, in this case two input lines are provided, one going to the grid of each tube, and a condenser I35 is connected between the two grids to aid in ensuring stability and correct operation. From the anode of tube I05, a line I3I connects to the grid of another similar tube I05 in the next emitter unit (2) and a further line I36 from the anode connects to the control grids of the two gates I34 and I33.

When the start control unit is key operated as described above, a negative pulse is applied to the grid of triode I05 via line 81 from tube Y (Figure 4). This pulse makes triode I05 non-conducting, and switches the trigger stage 105 and I32 over to the on" state with triode I32 conducting. From the anode'o'f triode I05 a positive pulse is applied to the control grids of gates I 34 and I33 via line I36. At this time the" line 36 conditioned by the half cycle control trigger I00, as described later, is at a potential nearly equal to the cathode potential of gate I34, while line 31 is considerably negative with respect to the cathode of gate I33. The control grids of both tubes are normally biased negatively by the connection to the bias line 4. Accordingly, the positive pulse on line I36 results in a negative pulse appearing at the anode of I34 on line 34b and no output at the anode of I33 on line 34, since the anode current is cut oil by the nega tively biased suppressor grid. Following this, a negative pulse is applied to the grid of triode I32 from the pulse generator via line 32, causing I32 to become non-conducting, thus switching the trigger stage I05, I32 back to the normal or "oil" state with triode I05 conducting which produces a negative pulse on line I3I, which is applied to the grid of the triode I05 in the next emitter unit 30(2), causing that trigger stage to switch on." This unit in turn will produce a pulse on the appropriate line 34b and then be switched back to the normal state by a negative pulse on line 33 (Fig. 1) from the pulse generator, thus switching emitter unit 30(3) to the "on" state. In this manner, the emitter units are successively switched to the "on state, and then back to the normal state. The odd numbered emitter units, that-is 30(1), 30(3), etc. are connected to line 32 as shown in Fig. l and the even numbered emitter units to line 33. As has been explained, pulses are produced alternately by the pulse generator on the lines 32 and 33, and thus sequential operation of the units is eiiected. Since triode I32 is normally non-conducting, the pulses from the pulse generator will only be effective to switch "oil" the unit which has already been switched "on.

The emitter units switch on and oif in succession until unit 30(19) is reached. When this unit switches ed, a negative pulse is sent via line Ill (Figs. 1 and 12) to enter the value "1" in the cycle counter 40 and a positive pulse is sent via line 38 (Figures 1 and 4) to the control grid oi gate Z in the start control unit. As described already, the suppressor grid of this gate is at this time at approximately cathode potential, so that this positive pulse on the control grid will produce a negative pulse at the anode, which will be transmitted via line 89 to the grid of triode I05 in emitter unit 30(1), see Figure 2, switchin this unit on and commencing another half cycle. Additionally, the line I3I from unit 30(19) goes to the half cycle trigger control unit I00 (Figure 1) serving to switch this unit to the "on" state. This results in the potentials of lines 36 and 31 being reversed, so that line 38 is now considerably negative and line 31 near cathode potential. Ac cordingly, during this half cycle the gates I 33 (Fig. 2) in each emitter unit will be operative to produce negative pulses on lines 35. It will be understood that operation continues in this cyclic fashion until the cycle counter 40 via its output line 80 (Fig. 4) resets trigger XY (Fig. 4) in the start control circuit, puttin the suppressor grid of gate Z below cutoif and thus preventing the transmission of the pulse from unit 30( 19) to unit 30(1) through gate Z.

In all the emitter units except unit 30(1) the two input lines 3'! and B9 arereplaced by the one line I3I from the next lower unit. It is required that two isolated outputs be obtainable from unit 30(6) so that a further gate similar to gate I 33 of Fig. 2 is provided, wired in parallel with I33, except for the anode circuit which provides the separate output shown as line 34a (Figure 1). For the units 30(17), 30(18) and 30(19), one output line only is required and the'gate I34 is omitted for (17) and (18) and gate I33 for (19) (see Figure 1). The emitter unit 30(19) also has the line 38 connected to the anode of triode I32 of higher, then the grids of the left hand triodes of E2, E4 and Eli are biased very considerably beyond cut off and the right hand triodes are biased just to cut off. Under these conditions, a positive pulse produced on line 25 by trigger #2 switching hack to the normal state, will overcome the bias of the right hand triode of E2 and produce a negative pulse at the anode of that triode but will be unable to drive the grid of the left hand triode of E4 more positive than cut-off, and hence no pulse will appear at the anode. The negative pulse at the anode 01' E2 is transmitted via line 26 to the grids of the trigger #1, through the two condensers I49 and I50, to switch the trigger over to the opposite state. Thus with tube A of trigger stage N conducting, the triggers #2. #4 and #8 of the register may eifect the switching of the next lower stage.

When tube B of trigger N is conducting, the left hand triodes of E2, E4 and EB will be operative by a positive pulse. A positive pulse for example from the anode of tube B of trigger #1 will be transmitted by the left hand triode E2 to trigger #2 to switch it to the opposite state. Thus in this case a trigger stage of the register is now able to effect switching of the next higher stage.

At the beginning of the second half cycle of multiplication, a negative pulse from the emitter unit 30(1) is transmitted to the grid of tube B of trigger N via line 65, to switch it to the normal state with tube A conducting. A negative pulse is next applied from the emitter unit 30(2) as described later to trigger #1 via line I2(1). If this trigger stage has been set, it will be switched back to the normal state and it it is in the normal state. it will be unafiected. A pulse is next applied via 30(3) to trigger #2 via line [2(2) to effect similar switching action. If the trigger is switched to normal, then a pulse will be transmitted via right hand triode E2 to set trigger #1, as already explained. since trigger stage N is set at this time to make the right hand E triodes operative. The remaining register trigger stages in a denomination are similarly pulsed successively, so that after this has taken place any of the triggers #2, #4, #8 set by entry will have set the next lower trig er and itself been returned to normal, that is, the

value will have been halved. In the case of trigger #1. however, provision must be made for efiecting an entry of five in the next lower denomination, if this #1 trigger was set by the entry.

The trigger #1 in each denomination, except the units, is without the resistor I and connecting line 69. Instead, line I2 is joined directly to the anode of tube A of trigger #1 and connects it via a condenser II (Figure '7) to the grid of tube A in carry trigger stage P. When trigger #1 switches back to the normal state. the resulting negative pulse switches carry trigger stage P "on! From previous description, it will be understood that the junction I5 of the two resistors I4 will rise in potential to bring the control grid of gate FI to approximately cathode potential. After th halving operation has been completed, a further emitter pulse on line 65 from (9) switches trigger N to the "on" state, making operative the left hand E tubes. emitter pulses on line 24 are applied to the suppressor grid of gate Fl, producing five pulses at the anode, which are transmitted to trigger #1 of the lower denomination by line I52, to efiect the entry of value five in this denomina- Five tlon. This is possible since the left hand E tubes are now operative; thus after two pulses, trigger #1 will set trigger #2. After four pulses trigger #1 will reset trigger #2, which will set trigger #4. The fifth pulse will set trigger #1 so that triggers #1 and #4 are now set, representing the value five. This example assumes that these trigger stages were unset before the application of the five pulses. Such carry circuits consisting of a trigger P and a controlled gate F1 are provided for each denomination except the units denomination. It will be appreciated that the carry circuit shown in Figure 7 is actually that which effects the carry between the tens and units denominations.

Since during the halving operation the trigger stages are pulsed via the lines I2 in the order I, 2, 4, I3, each stage in a register order will have been reset prior to the time at which it may be set by the resetting of the next higher trigger stage of the same order. Furthermore, the carry of value live to the next lower denomination, occurs aiter the completion of the halving operation, at which time the maximum value which may be standing in the register is four, so that after the addition of the carry. the maximum value is nine.

In the lowest denomination, no carry circuit is required. but it is necessary to determine whether trigger #1 is in the on or oil state, to indicate whether the value in the multiplier register is odd or even. This function is performed by pentode F2 and trigger stage Q (Figure 7). The resistor I53, and the two resistors 10 form a. potentiometer between line 2 and line I5. When trigger #1 is on, tube A is nonconducting, and the control grid of pentode F2 assumes a potential approximately equal to that of the related cathode. The suppressor grid of F2 is normally biased to cut oil by the connection to the bias line 4. However, if a positive pulse from the emitter is applied to the suppressor grid via line H, and at the same time the control grid is near cathode potential, a negative pulse is produced at the anode of pentode F2. This pulse is applied to the grid of triode A of trigger stage Q, cutting A 05 and switching the trigger "on. The three resistors I54, I 55, I56, form a potentiometer between line 2 and line I5, so that when triode A becomes nonconducting. the potential of line 41 (see also Fig. 1) rises. Line 41 is connected to the product transfer tubes 44 so that when trigger #1 of the units denomination of the multiplier register is on," the increased potential of this line 47 allows the transfer tubes 44 to become operative to transfer the values in the multiplicancl register to the products counter.

M ultiplicand register One denomination of the multiplicand register indicated generally as 42 in Fig. 1 is shown in detail in Figure 8. It consists of four trigger stages, similar in general to those of the multiplier register. representing the values 1, 2, 4, 8. The initial entry is made by applying a negative voltage to the appropriate lines I, 2, 6, 8 of the group II.

The carry circuit between denominations comprises the trigger stage C (Figure 8) and Ya gate GI and is indicated as I51 in Figure 1. The control grid of pentode GI is biased negatively by connection through resistor 96b to the junction of resistors 96 and 96a which form a potentiometer between the bias line 4 and line I. If trigger #8 is switched from "on to "ofi, a posi- 13 tive pulse will be produced on line 6 and transmitted to the control grid of gate GI. At the time when a carry is to be accepted, line 23 from the emitter is holding the suppressor grid of GI (see Voltage to Open Gates G! and G4, Fig. 13) at approximately the same potential as the cathode. Accordingly, the positive pulse on the control grid of GI produces a negative pulse at the anode which is transmitted via line 9 to the grid of tube A of carry trigger C to switch this trigger on." 'After the doubling operation has been completed as described presently. a negative pulse from the emitter is applied via line '20 to the grid of tube B of trigger state C (seePul'se to Reset Triggers C in 42 and 43 and Trigger P in "4|, Fig. 13) to reset it back to the normal state. The resulting conduction of tube A produces a negative pulse on line 2 I, which is-t'ransmitted to the grids of trigger #1 of the next -higher denomination, as indicated by line 21a in Figure 8, effecting the switching of this trigger and so entering the value one.

The doubling of the value in the MC register is effected by applying negative pulses in succession (see Pulse to Multiplier #1 and Multiplicand #8, etc. Fig. 13) alongthe lines I2 in the order 8, 4, 2, 1. If trigger #8 of multiplicand is on, then the negativepulse applied by line l2(8) to the grid of tube B Willswitch it to the normal state, and the carry trigger stage C will be set, as already described. If trigger #4 of the multiplicand is on," then in switching over it will produce a negative; pulse on line l0 which will switch "trigger #Bfon. A similar action occurs with'trigger t2; which may be set trigger #4. In the case of trigger #1, in switching to normal it will produce a positive pulse at the anode of tube B, which, 'via line 5, will be transmitted to the left hand grid of the double triode isolating valve D. This will produce a negative pulse at'the anodefwhich, via line 7, will cause theswitching of trigger #2.

Although decimal values, expressed in the binary code 1. 2, 4, 8 have been entered in the register, the register is a binary counter registering up to 16. Hence, after doubling has taken place, the values may no longer be correctly represented in a decimal scale, and a correction must be performed in the following manner. Firstly, three positive pulses from-the emitter (6) (7) (8) of emitter and auxiliary'control 54 are transmitted via line I! to the right hand grid of double triode D. Three negative pulses are produced at the anode and via line I, switch the trigger #2 three times, thus entering 6 into the register. The value in the register has now been corrected to a scale of 16; and if the value initially was greater than 9 and *less than 16, the carry trigger C will have been set and the correct decimal remainder will be registered For example, if the original vaiue was 14, then after the addition of 6, a carry will be registered together with a value of 4. If, however, the-original value was 9 or less, then no carry will have been registered and the value standing in the register will be too great by 6. To obtain the correctregistration, a second additionmust be made, this time of the value 10. Thus a total of 16 will have been added, and since the register counts to sixteen, the original entry vaiue'win rsult,and thus the correctvalue will be obtained, provided that the carry stag'eis rendered'inoperati've during this addition, to prevent the registration'of the false carry which is produced. For example, if

14 the original entry was 4 the addition of 6 gives the value 10, a further addition of 10 gives the value 2!), which is registered as 4 and a false carry, which is suppressed.

The'addition of ten is carried out as follows. If the trigger stage C has not been set, then tube B will be non-conducting and the control grid of gate G2 will be brought to approximately the same potential as the related cathode, by the connection of the junction of the two resistors l4. Five positive pulses from the emitter are transmitted to the suppressor grid of valve G2 by line 26, producing five negative pulses at the anode which are transmitted to the grids of trigger #2 by line I to switch the #2 trigger five times, thus entering the value ten. At this time, the voltage of line 23 has been lowered to keep the suppressor grid of gate GI below cut-oil? and thus prevent the transmission of a pulse from trigger #8 to carry trigger C. If the carry trigger C has been'set prior to the addition of ten, the control grid of gate G2 will be held below cut off potential, so that although five pulses are applied to the suppressor-grid, they will not appear at the anode and an entry of ten will not occur.

When a duo-decimal-register is required, as for example for dealing withpence, then four and twelve are added instead of six and ten, in order to obtain a correct registration. Thus, in the duo-decimal system considering the previous examples, an entry of 14, after theaddition of 4, becomes a registration of 2 and a-carry; an entry of a after the addition of 4 becomes 8, and after the adidtion of 1'2,-becoines 20, which gives a registration of 4 and a carry, which is-suppressed. In order to effect the entry of 4 in the register, a negative pulse from the emitter is applied via line 34a to the grids of trigger #4, while line H is not connected in that denomination (Figures 1 and 8) The anode of gate G2 is disconnected from line I and connected to the junction l3 of the two condensers of trigger #4. Three pulses instead of five are applied to line 18 which physically replaces line 24 (see Fig. 1). thus entering the value twelve in the register.

When any of the triggers is on, tube A will be non-conducting and the potentialrat the junction of the resistors I58 :and IE!) will be at approximately the potential of line I. Through the lines 48, the grid of the related product transfer valve (M of Fig. 1) will be maintained at approximately cathode potential, since the cath odes of all these valves are connected to line I. When tube A is conducting, the line 48 becomes sufiiciently negative in potential to ensure that the grid of the related transfervalve 44 is below cut off.

Product counter This counter is indicated generally as i3 5. .1 Figure 1 and shown in detail in Figures 9 and ii.

Each denomination of the counter consists of four trigger stages, representing the values 1. 2, 4. 8. Entry is-effected by applying the appropriate number of pulses to the line 5i. There are four product transfer tubes 44 for each denomination (Figure 1). They are jointlycontrolled by the triggers of the multiplicand register 42 and the odd-even detector unitF-Z andQ,-in the manner already described. In addition, the screen grid of each transfer tube #l'is connected to the line 50(1), and similarly the groups of transfer tubes #2, #4, and #8 are connected to the lines 58(2), 58(4) and 50(8). These lines are connected directly to the anodes of the appropriate amplifying tubes '48. Each tube 46 is normally at zero bias and so conducting heavily, thus producing a large potential drop across the anode load re sistor. When a negative pulse is applied to the grid of a tube 45 from the emitter via line 341), the tube is cut off and the anode potential rises. If the control grid and suppressor grid of a pentode 44 have been brought near cathode potential, then the positive pulse on the screen grid transmitted to it by line 50 will produce a negative pulse at the anode, which single pulse will be applied to a trigger #1 of the product counter via line Eight pulses are provided by a tube 45 on line 59(8), so that if any of the pentodes 44(8) have been prepared for operation by the inultiplicand register and the odd-even detector, eight pulses will be transmitted via line 5| to enter eight in the related denomination of the product counter. The values 1, 2, and 4 are similarly entered.

The setting of trigger #2 by trigger #1 is effected through tube E (Figure 9). The connection of trigger #2 to #4 and #4 to #8 is via the lines Ill, as in the multipllcand register.

It is necessary to enter 6 and into the product counter for correction in the decimal denominations as in the multiplicand register. The value 6 is entered by applying three pulses to line I! to flip the #2 trigger 3 times. The value 10 is entered by applying five pulses on line 24, the gate G3 being controlled by the setting or non-setting of the trigger carry stage C in the same way as gate G2 in the multiplicand register. In similar manner, 4 and 12 are entered in the pence duo-decimal denomination. A single pulse is applied to line 34a and transmitted to trlgger #4 by tube S, to enter 4. Three pulses are transmitted to gate G3 via line [8 which also is connected to trigger #4 to cause the entry of 12 (see pence order Fig. 11).

When trigger #8 is switched over from the "on" state to normal, 3, positive pulse is applied to the control grid of G4, producing a negative pulse at the anode, which is transmitted via line 19 to the grid of tube A of carry trigger stage C to set it. With tube A of trigger C non-conductin the control grid of gate G5 is brought to approximately the potential or line I. At a. later stage, a. positive pulse is applied to the suppressor grid of gate G5 via line 82 and ii the carry trigger stage C is set, a negative pulse will be produced at the anode of G5 and transmitted by line 83 to trigger #1 of the next higher denomination. This is indicated by the connection 33a to trigger #1 of Figure 9.

All the gates G5 receive a pulse on line 82 at the same time, so that all the carries are entered at the same time. If any of the denominations are standing at 9 (decimal) or 11 (duo-decimal), then the addition of the carry will generate a further carry. This possible further carry is dealt with by the gate G6. Before a pulse has been applied to line 82, the potential of line 84 is raised and continues raised for a while after line 82 has been pulsed (see Voltage to Open Gates G6, Fig. 13). If trigger #8 now switches from the on" state to normal, 9. positive pulse is transmitted directly to the control grid of gate G6 via line 18. The resulting negative pulse at the anode is transmitted via line 83 to the trigger #1 of the next higher denomination.

The connection of the various denominations of the products counter is shown in schematic from in Figure 11. The pence denomination is connected for duo-decimal operation, the shill- 16 ings for decimal, the tens of shillings or counting to two, and the pounds and tens of pounds for decimal operation.

Operation of complete multiplying device In order to show the functioning of the multiplying device as a whole, one complete multiplying cycle, comprising two complete emitter cycles, will now be described.

A gate will be described as being operative" when the electrode potentials are such that, on applying an operating pulse. a pulse is produced at the output electrode, which is normally the anode. The expression "partially operative" will be applied to a gate in which control potentials are applied to more than one electrode and in which not all of the electrode potentials are such as to make the gate operative. An example of this condition is a. product transfer tube 44 in which the suppressor grid is at approximately cathode potential but the control grid is more negative than the cut-off value. A gate will be described a inoperative" when an operating pulse produces no pulse at the output electrode, and all control electrodes are more negative than cut oil potential.

The multiplying operation will be sub-divided into a sequence of steps, each step representing one operation of one of the emitter units 30.

By way of illustration, it will be assumed that the multiplier (MP) equal to -99- and multiplicand (MC) equal to 9, 18s., 2d. of the numerical example previously given, have been entered into the appropriate registers.

Reference may be had particularly to Figures 1 and 1a showing the interconnection of the various units already described in detail and to Figure 13, which briefly describes the function and illustrates the relative time relationship of the various control voltages and operating pulses.

On depression of the start key (Figure 4), the trigger stages UV and KY are switched over to produce a negative pulse on line 81 and to make gate Z operative. The half cycle control unit III!) is in a state such that gates l34 (Fig. 2) of the emitter units 30 are operative.

STEP 1 Emitter unit 30(1) is switched "on" by the pulse on line 81. The resulting pulse on line 34b is amplified and inverted in polarity by amplifier 46 (Fig. la) and applied (see Pulse to Odd-Even Detector to Set it. Set for Odd, Fig. 13) via line 11 to odd-even detect tube F2 (see also Fig. 7). Since an odd number (99) is standing in the multiplier register, trigger #1 of the units denomination is on, rendering tube F2 operative. Thus the pulse on line 11 will via tube F2 cause trigger Q to switch on," raising the potential of line 41 and making all the transfer tubes 44 partially operative.

The same pulse from emitter unit 30(1) via line 34b will switch the trigger stage of the connected auxiliary control unit 55 on, raising the potential of line 23, to make operative the gates GI in the carry circuits of the multiplicand register and gates G4 in the carry circuits of the product counter (see Voltage to Open Gates G1 and G4, Fig. 13).

The multiplicand register contains the value 9:18:2d. so that via the lines 48, the following transfer tubes 44 will be made fully operative:

Connected to the pence denominatlon-pentode 44(2).

17 Connected to the shilings denominationpentode 44(8).

Connected to the tens of shillings denomination-pentode 44(1).

Connected to the units of pounds denomination-pentodes 44(1) and 44(8).

Connected to the tens of pounds denomination-none.

Finally a pulse on line 32 from the pulse generatoi- 3| switches emitter unit 30(1) back to normal, producing a negative pulse on line (3|.

STEP 2 Emitter unit 30(2) is switched on by this pulse on line I31. The negative emitter pulse is amplified and inverted by tube 46 connected to line 34b from 30(2) and transmitted via line 50(8) to the screen grids of the transfer tubes 44(8). The pentodes 44(8) are operative only in the units of shillings and units of pounds denominations, so that one pulse will be fed to these product counter denominations, efiecting an entry of one (see Pulses for Transferring into Product Counter, Fig. 13).

A pulse on line 33 from the pulse generator 3! will switch emitter unit 30(2) back to normal. producing-a negative pulse on line It.

STEP 3 Emitter unit 30(3) will be switched on by the pulse on line (3| from unit 30(2). The resulting negative pulse passes through thesame amplifier 46 and via line 50(8) adds-another one into the same denominations.

STEP 4 To STEP 9 INCLUSIVE By the successive switching of emitter units 30(4) to 30(9), a further six pulses are sent via line 50(8) to add a total of eight in the product counter.- Thus the units of shillings and units of pounds denominations each register a value of -8-.

STEP 1o Emitter unit 3000) is switched on by unit 30(9) and a pulse is transmitted via its connected line 341), a second amplifier 46 and line 50(4) to the screen grids of all the transfer tubes 44(4) Since none of these valves is fully operative, no pulse will be produced on lines STEP 11 o STEP 13 INCLUSIVE .Three further pulses are transmitted along line 50(4) by the switching of the emitter units 30(11) to 30(13) inclusive, but are not effective to make an entry in the product counter.

STEP 14 A pulse from emitter unit 30(14) is transmitted via its line 34b, an amplifier 46 and line 50(2) to the transfer tubes 44(2). The tube 44(2) in the pence denomination is operative, so that an entry of one is made.

STEP

A second pulse is transmitted to the transfer tubes 44(2) from emitter unit (15) to enter a further one into the pence denomination of the product counter. The value now registered is 8:8:2d.

STEP 16 A pulse from emitter unit30(16) -istran smitted via itsline 341), an amplifier 45 and line (1) to the transfer tubes 44(1). The tubes 44(1) .in the tens of shillings and units of pounds denominations are-operative, so that entries of one are effected in these denominations. Accordingly, the value registered in the-product counter willnow be 9:18:2d., that is, the transfer of the value from the multiplicand register to the product counter has been completed once.

STEP 1'! AND STEP 18 The emitter units 30(17) and 30(18) switch "on" and back to normal, but since they have no gates I34 their pulses are not utilized on this half cycle to control any machine operations.

STEP 1!) The negative pulse from emitter unit 30(19) is transmitted via line H! to the cycle counter 40 (see Pulse to Start Unit 39 and Cycle Counter 40, Fig. 13) to effect an entry of one. When the emitter unit 30(19) is switched oil by the negative pulse on line 32, a negative pulse is transmitted via line .131 to switch over the half cycle control unit (00, so that the gates 133 (Fig. 2) are now made operative (see Voltage from I00 to Open Gates I33, Fig. 13) and the gates I34 rendered inoperative. A positive pulse is also transmitted via line 30 to the grid of gate Z (Figure 4) in the start control unit. The negative pulse thus produced at the anode of gate Z via line 89 switches emitter unit 30(1) "on" and so commences the second half of the multiplier cycle.

.STEP 20 The negative pulse on line 34 from emitter unit 30(1) serves via line 05 (Figs. 1 and '7) to reset the odd-even detector trigger state Q, and also resets off :the trigger stage N which controls the .dual triodes E2, E4 and E0 in the multiplier register (see Pulse to Trigger Q and Trigger N, Fig. 13) the line 34 being directly connected to line of Figure '7. When trigger Q is thus reset, the suppressor grids of all the transfer pentodes 44 (Fig. 1) are made more negative preventing any further transfer from the multiplicand register to the product counter. With triode A of trigger N conducting, the right hand tubes of dual triodes E are operative for halving the multiplier.

STEP 21 The negative pulse from emitter unit 30(2) is applied vialine 34 to the triggers #8 of the multiplicand register (see Pulse to Multiplier #1 and Multiplicand #8, Fig. 13) this line being connected to the lines 12(8) (Figure 8 in each denomination. The trigger #8 is set in the units of shillings and units of pounds denominations, so that the pulse will switch these trigger stages to normal, and thus the carry trigger stages C will beset, GI having been made operative at step 1.

The line 34 of emitter unit 30(2) also connects to the line 12(1) in the two denominations of the multiplier register. Both triggers #1 are on" and will be switched "ofF by the pulse. Since the left hand tubes of dual triodes are not operative, the units denomination triggerstage will not affect any of the other stages. The tens denomination trigger #1 will send .a pulse via line 1 2 as described abovefor all orders above the units order to switch the carry triggerstage P on for subsequent 5s carry to the unitsorder.

STEP 22 The pulse from emitter unit 30(3) via lines 34 and (2(4) will be enabled to reset the triggers #4 in the multiplicand register and via lines 34 and [2(2) will beenabled to reset the triggers #Zdn .the multiplier register. Since in this examplenone of these triggers is on. no change will bemade.

STEP 23 The pulse from emitter unit 30 (4) will eiiect resetting of the triggers #2 in the multiplicand register and triggers #4 in the multiplier register. In the multiplicand register, pence denomination trigger #2 being switched to normal, will switch trigger #4 to the "on state.

STEP 24 The emitter pulse from emitter unit 30(5) will effect resetting of triggers #1 in the multiplicand register and triggers #8 in the multiplier regis ter. As a result, in the multiplicand register, a carry will be registered in the tens of shillings denomination and value 2 in the units of pounds denomination. In the multiplier register, by the halving process value 4 will be registered in both units and tens denominations.

The halving and doubling operation has now been completed, apart from the addition of carries. The registers now contain the following values:

Multiplicand:

Pence 4 (step 23) Units of shil1ings and carry (step 21) Tens of shillings 0 and carry (step 24) Units of pounds 2 and carry (step 24 and step 21) Tens of pounds- 0 Multiplier:

Units 4 (step 24) Tens 4 and carry (step 24 and step 21) STEP 25 The pulse from emitter unit 30 (6) is transmitted viaqine 34a to trigger #4 of the pence denomination (see Pulses to Pence Triggers #4, Fig. 13) of the multiplicand register and via line 34a (Fig ure 9) and tube S to the trigger #4 of the pence denomination of the product counter. thus effecting the corrective entry of four of these two pence denominations. At the same time, the pulse via tine 34 and the connected auxiliary control unit 54 via lines I! effects the corrective entry of two in the shillings and pounds sections of the product counter and via lines I] and dual triodes D (Fig. 8) to effect the corrective entry of 2 in the denominations of the MC counter.

STEP 26 AND STEP 2":

The pulses from emitter units 30(7) and 30(8) efiect two further entries of two in all the decimai denominations of the MC and of the product counter so that a total correction of six has now been entered.

The values standing in the registers at this time are:

Multiplicand:

Pence 8 Units of shillings 6 and carry Tens of shillings 0 and carry Units of pounds 8 and carry Tens of pounds 6 Multiplier:

Units 4 Tens 4 and carry STEP 28 The negative pulse from emitter unit 30(9) is transmitted via line 66 (see Pulses to Multiplier Register to Carry up Line 66, Fig. 13) to switch on trigger stage N of the multiplier register, thus making the left hand triodes of dual triodes E 20 operative. The pulse also sets auxiliary control unit 55 connected to 30(9) and line 84 is raised in potential to make gates GB of the product counter operative for carry on carry (see Voltage to Open Gates G6, Fig. 13).

s'rnr 29 The pulse on line 34 from unit 30(10) is in verted by the amplifier 46 and transmitted via line 82 (see Carry Pulse to Product Counter Line 82, Fig. 13) to the suppressor grids of gates G5 (Figure 9) of the product counter. If any of the carry trigger stages C have been set, then the related gate G5 will be operative and a carry pulse will be transmitted to trigger #1 of the next higher denomination. Gates GB for carry on carry are also operative (step 28) to deal with any successive carries that may occur.

The auxiliary control unit 55 which is also connected to 30(1) is now switched over to lower the potential of line 23 to block carry tubes GI and render gates G4 inoperative (see Pulse to Unit 55 to Close GI and G4, Fig. 13).

STEP 30 There is no outlet for a pulse from unit 30(11) on this half cycle.

STEP 3].

The pulse from emitter unit 30(12) resets the auxiliary-control unit 55 connected to 30(9) to make inoperative the carry on carry gates G5 in the product counter.

STEP 32 The pulse from emitter unit 30(13) via auxiliary control unit 50 and pentode Fi (Fig. 7) if this has been made operative by carry trigger P being on," enters a carry down value oi one out of five into the units denomination of the multiplier register. At the same time. via line 24 and gates G2 and G3 in the decimal denominations of the multiplicand register and product counter, the corrective value 2 out of 10 is entered provided carry has not been set (see Pulses to Add 10 in Registers and Counter Decimal, Fig. 13).

STEP 33 A further entry of a carry down value of one is made in the multiplier register under control of 30(14). A further corrective value of two is also made into the multiplicand register and product counter provided of course carry has not been set.

STEP 34 As for step 33 but under control 30(15) and in addition a pulse via auxiliary control unit 54, line l0 and gates G2 and G3 enters a corrective four out of 12 into the duo-decimal denominations (see Pulses to Add 12 Duo-Decimal, Fig. 13) of the multiplicand register and product counter.

STEP 35 AND STEP 36 As for step 34 but under control of 30(16) and 30(17) respectively. Thus after step 36, a carry down of five has been entered in the units denomination of the multiplier register, a corrective ten, if required, in the decimal denominations and a corrective twelve. if required, in the duodecimal denominations of multiplicand and product. However, as has already been described. these entries are actually efiective only in those denominations of the multiplicand and product 21 in which no carry has been registered. Accordingly the values now registered are:

Multiplicand:

Pence 4 (8+12) Unit of shillings 6 and carry Tens of shillings and carry Units of pounds 8 and carry Tens of pounds 0 (6+l0) Multiplier:

Units 9 (4+5) Tens 4 It will be noted that no carries occur during the addition of 10 or 12, since the carry gate valves are inoperative.

s'rnr 37 The pulse from emitter unit 30(18) via line 34 and line 20 effects resetting of the carry trigger stages C of the register 42 to produce carries of carry trigger stage C of counter 43 and of the carry trigger stage P of register 4| to reset them ready for carry (see Pulse to Reset Triggers C in 42 and 43 and Trigger P in M, Fig. 13).

Thus the final values are:

Multiplicand:

Pence 4 Units of shillings u 6 Tens of shillings 1 Units of pounds 9 Tens of pounds 1 Multiplier:

Units 9 Tens 4 Product Pence 2 Units of shillings 8 Tens of shillings 1 Units of pounds 9 Tens of pounds 0 It may be noted that it is possible to effect carries in the multiplicand register by resetting th carry triggers C at this time,- since the values registered must be even, owing to the doubling, and therefore the addition of a carry in any denominational cannot cause a further carry.

Seven further complet multiplying cycles are carried out before the cycle counter 40 prevents further cycling, and the product of lb980 18s. 6d. will then be standing in the product counter. It will be understood that in order to accommo date the full product, a further denomination for the hundreds of pounds will be required (not shown in Figure 1a) similarly connected to that for the tens of pounds.

It has been found that the following types of valves and values of components provide satisfactory operation:

The cathode follower tubes J, K and M are Type 6J5.

The amplifier tubes 46 are Type 6V6.

All other triodes are Type GSN'I.

All other pentodes ar Type EF50.

All resistors such as I28 from the anode of a tube to line 2 are 22,000 ohms.

All resistors such as I08 from the control grid of a tube to line I are 50,000 ohms.

All cross coupling resistors such as I26 in trigger stages ar 100,000 ohms.

All voltage divider resistors such as I41 are 220,000 ohms.

All voltage divider resistors such as I66 are 440,000 ohms.

Resistor MI is 220,000 ohms.

Resistors I39 and I6I are 50,000 ohms.

Resistors 9| are 100,000 ohms.

Resistor I 62 is 22,000 ohms.

Resistor IE3 is 50,000 ohms.

Resistors I 43 are 220,000 ohms.

Resistor 96 is 20,000 ohms.

Resistors 96a. 96b. 96c and 9'! are respectively 50,000 ohms, 20.000 ohms, 50,000 ohms and 50,000 ohms.

Condensers H0 and III are 600 micromicrofarads.

Condensers such as I25 and I24 in the grid couplings of trigger stages are 200 micrornicrofarads.

Condensers such as I35 in the grid couplings of trigger stages are 25 micromicrofarads.

Condensers such as I22 and I23 in the grid input coupling of trigger stages are micrornicrofarads.

Condensers I64 and I65 are 50 microniicrofarads.

Condenser I is 50 micromicrofarads.

Condensers I67 and IE8 are 50 rnicromicrofarads.

Condensers I10 are 10,000 micromicrofarads.

Condenser IN is 32 microfarads.

In the circuit so far considered, fifteen pulses were provided for reading out into the #1 triggcr stage of each denomination of the product counter. This involved the use of three controlling electrodes on the gates 44 between the multiplicand register 42 and the product register 43. Considerable simplification of this transfer is possible where the values to be entered in the product register may be entered by pulsing any one or more of the four trigger stages of a denomination of the product register. In this modification, the product transfer pentodes 44 for each denomination are jointly controlled by the odd-even detector F2 and Q as before, and each pentode 44 by the associated trigger stage of the multiplicand register as before, but the screen grids are all connected via a resistance to the main H. T. line This therefore dispenses with the fifteen pulses previously required to be entered from the emitter and enables the emitter stages to be correspondingly reduced in quantity. The anodes therefore of these tubes 44 have separate anode loads instead of four in each denomination being connected in common. Each separate anode is connected via a condenser to a trigger stage in the product register having the same value as the trigger stage in the multiplicand register controlling on the grid of the transfer tube M. Therefore, as previously described. the multiplicand trigger stages, if "on," are switched "off" in the order #8, #4, #2, #1, by the emitter steps 2, 3, 4, 5 in second half cycle. Those so switched will produce a positive pulse which is applied to the control grids of the transfer tubes. The suppressor grid, being controlled from the odd-even control will, it odd, allow a negative pulse at the anode of 44. Thus a #8 trigger stage of the multiplicand register may apply a pulse to switch the #8 trigger stage of the product counter in the same denomination in lieu of providing eight pulses for operating the #1 trigger stage in this denomination. The pulses to the multiplicand #8, #4, #2, and #1 trigger stages occur prior to the carry pulse to the product counter on line 82 (emitter step 10 of second half cycle). By reason of the values of the multiplicand being scanned in the order #8, #4, #2, #1, no difficulty occurs from the intermediate carries in the product register.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to preferred embodiments, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention. therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. An electronic converter for converting a static combinational code electronic representation of a value to a series of pulses representative of said value comprising a plurality of tubes each representative of a descending binary value. which together represent a binary coded digit, means selectively statically conditioning certain of said tubes in combination whereby the combinationally combined indications of all conditioned tubes statically represents a value to'be converted, a source of timed pulses. and means applying to each of said tubes selectively and WILLIAM WOODS-HILL. DAVID THOMAS DAVIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Desch et al. June 4, 1946 Number 

